package cn.edu.sdjzu.xg.bysj.controller.basic;

import cn.edu.sdjzu.xg.bysj.domain.Teacher;
import cn.edu.sdjzu.xg.bysj.service.TeacherService;
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;
import com.alibaba.fastjson.serializer.SerializerFeature;
import lombok.extern.slf4j.Slf4j;
import util.Condition;
import util.ControllerHelper;
import util.JSONUtil;
import util.Pagination;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.sql.SQLException;
import java.util.Collection;
import java.util.List;

/**
 * @author TG.SI@188.com
 * @version 1.0  10-25-2020
 * <p>
 * Teacher Controller
 */
@Slf4j
@WebServlet("/teacher1.ctl")
public class TeacherController extends HttpServlet {
    /**
     * 把一个或所有符合条件教师对象以分页的形式响应到前端
     * @param request
     * @param response
     * @throws ServletException
     * @throws IOException
    可能的请求
    {"id":1}
    可能的请求
    {
        "pagination": {
        "pageNo": 2,
        "pageSize": 2
        },
        "conditionList": [{
            "value": "9",
            "key": "name",
            "operator": "LIKE"
            },
            {
            "value": "9",
            "key": "department_id",
            "operator": "="
            }
        ]
    }
    */
    @Override
    protected void doGet(HttpServletRequest request,
                         HttpServletResponse response)
            throws ServletException, IOException {
        //创建JSON对象respMessage_jsonObj，以便往前端响应信息
        JSONObject respMessage_jsonObj = new JSONObject();

        //设置响应字符编码为UTF-8
        response.setContentType("application/json;charset=UTF-8");

        //将request body转换为JSON字串
        String req_jsonStr = JSONUtil.getJSON(request);

        //将request body解析为JSONObject对象
        JSONObject req_jsonObj = JSON.parseObject(req_jsonStr);
        //如果请求body为空
        if (req_jsonObj == null) {
            respMessage_jsonObj.put("message","未收到请求信息！");
            response.getWriter().println(respMessage_jsonObj);
            return;
        }
        //从JSONObject对象中读取键“id”的值（Java Object对象），req_jsonObj可能是{"id":1}
        Object id_obj = req_jsonObj.get("id");
        try {
            //如果id_Obj != null, 说明请求数据有id键，是请求某个教师对象
            if (id_obj != null) {
                int id_int = Integer.parseInt(id_obj.toString());
                responseTeacher(id_int, response);
            } else {
                //请求中包含条件和分页信息，需要响应多个教师对象
                //读取分页信息，形成分页对象
                //从JSONObject对象中读取 “pagination” 键对应的值(JSONObject对象)
                Pagination pagination = ControllerHelper.getPagination(req_jsonObj);
                //从请求JSONObject对象中读取键“conditionList”对应的值(描述查询条件的JSONArray对象)
                List<Condition> conditionList = ControllerHelper.getConditions(req_jsonObj);
                //响应多个教师信息，其中conditionList, pagination两个对象引用为空是可能的
                this.responseTeachers(response, conditionList, pagination);
            }
        } catch (SQLException e) {
            respMessage_jsonObj.put("message", "数据库操作异常");
            //响应respMessage_jsonObj到前端
            response.getWriter().println(respMessage_jsonObj);
            //打印异常栈，方便调试（要用log4j代替）
            log.debug(e.getMessage());
        } catch (Exception e) {
            respMessage_jsonObj.put("message", "网络异常");
            //响应respMessage_jsonObj到前端
            response.getWriter().println(respMessage_jsonObj);
            //打印异常栈，方便调试（要用log4j代替）
            log.debug(e.getMessage());
        }
    }

    //按分页信息响应符合条件的教师对象和对象总数
    private void responseTeachers(HttpServletResponse response,
                                  List<Condition> conditionList_json_str,
                                  Pagination pagination)
            throws ServletException, IOException, SQLException {
        //分页获得满足条件的所有教师
        Collection<Teacher> teachers = TeacherService.getInstance()
                .findAll(conditionList_json_str, pagination);
        //第二个参数可以防止循环引用
        String teachers_jsonStr = JSON.toJSONString(teachers,
                SerializerFeature.DisableCircularReferenceDetect);
        //创建JSON对象resp_jsonObj，以便往前端响应综合信息
        JSONObject resp_jsonObj = new JSONObject();
        resp_jsonObj.put("totalNum", pagination.getTotalNum());
        resp_jsonObj.put("data", teachers_jsonStr);
        //响应resp_jsonObj到前端
        response.getWriter().println(resp_jsonObj);
    }

    //响应一个教师对象
    private void responseTeacher(int id, HttpServletResponse response)
            throws ServletException, IOException, SQLException {
        //根据id查找教师
        Teacher teacher = TeacherService.getInstance().find(id);
        String teacher_jsonStr = JSON.toJSONString(teacher);
        //响应teacher_json到前端
        response.getWriter().println(teacher_jsonStr);
    }

    //请使用以下JSON测试增加功能
    //{"teacher":{"description":"博士","id":1,"no":"01","remarks":""},"department":{"description":"信息管理","id":2,"no":"0202","remarks":"","teacher":{"description":"管理工程","id":2,"no":"02","remarks":"最好的教师"}},"id":7,"name":"id=7 的新的新老师","title":{"description":"副教授","id":2,"no":"02","remarks":""}}
    //请使用以下JSON测试修改功能
    //{"description":"修改id=1的老师
    //{"teacher":{"description":"博士","id":1,"no":"01","remarks":""},"department":{"description":"信息管理","id":2,"no":"0202","remarks":"","teacher":{"description":"管理工程","id":2,"no":"02","remarks":"最好的教师"}},"id":1,"name":"修改id=1的老师","title":{"description":"副教授","id":2,"no":"02","remarks":""}}

    /**
     * POST, http://localhost:8080/teacher.ctl, 增加教师
     * 增加一个教师对象：将来自前端请求的JSON对象，增加到数据库表中
     *
     * @param request  请求对象
     * @param response 响应对象
     * @throws ServletException
     * @throws IOException
     */
    @Override
    protected void doPost(HttpServletRequest request,
                          HttpServletResponse response)
            throws ServletException, IOException {
        //设置请求字符编码为UTF-8
        request.setCharacterEncoding("UTF-8");
        //根据request对象，获得代表新增Teacher的JSON字串
        String req_teacherToAdd_jsonStr = JSONUtil.getJSON(request);
        //将JSON字串解析为Teacher对象
        Teacher teacherToAdd = JSON.parseObject(req_teacherToAdd_jsonStr,
                Teacher.class);
        //前台没有为id赋值，此处模拟自动生成id。如果Dao能真正完成数据库操作，删除下一行。
        teacherToAdd.setId(4 + (int) (Math.random() * 100));

        //设置响应字符编码为UTF-8
        response.setContentType("application/json;charset=UTF-8");
        //创建JSON对象respMessage_jsonObj，以便往前端响应信息
        JSONObject respMessage_jsonObj = new JSONObject();
        try {
            //在数据库表中增加Teacher对象
            TeacherService.getInstance().add(teacherToAdd);
            respMessage_jsonObj.put("message", "增加成功");
        } catch (SQLException e) {
            respMessage_jsonObj.put("message", "数据库操作异常");
            //打印异常栈，方便调试（要用log4j代替）
            log.debug(e.getMessage());
        } catch (Exception e) {
            respMessage_jsonObj.put("message", "网络异常");
            //打印异常栈，方便调试（要用log4j代替）
            log.debug(e.getMessage());
        }
        //响应respMessage_jsonObj到前端
        response.getWriter().println(respMessage_jsonObj);
    }

    /**
     * DELETE, http://localhost:8080/teacher.ctl?id=1, 删除id=1的教师
     * 删除一个教师对象：根据来自前端请求的id，删除数据库表中id的对应记录
     *
     * @param request
     * @param response
     * @throws ServletException
     * @throws IOException
     */
    @Override
    protected void doDelete(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //将request参数转换为JSON字串
        String request_json_str = JSONUtil.getJSON(request);
        //将请求body解析为要删除的Teacher的id对应的JSONObject对象(可能是{"id":1})
        JSONObject idOfTeacherToDelete_jsonObj = JSON.parseObject(request_json_str);
        //从JSONObject对象中读取键“id”的值（Java Object对象），
        Object id_obj = idOfTeacherToDelete_jsonObj.get("id");
        int id_int = Integer.parseInt(id_obj.toString());
        System.out.println("id=" + id_int);//用于调试，要使用log4j代替
        //设置响应字符编码为UTF-8
        response.setContentType("application/json;charset=UTF-8");
        //创建JSON对象respMessage_jsonObj，以便往前端响应信息
        JSONObject respMessage_jsonObj = new JSONObject();
        try {
            //到数据库表中删除对应的教师
            TeacherService.getInstance().delete(id_int);
            respMessage_jsonObj.put("message", "删除成功");
        } catch (SQLException e) {
            respMessage_jsonObj.put("message", "数据库操作异常");
            //打印异常栈，方便调试（要用log4j代替）
            log.debug(e.getMessage());
        } catch (Exception e) {
            respMessage_jsonObj.put("message", "网络异常");
            //打印异常栈，方便调试（要用log4j代替）
            log.debug(e.getMessage());
        }
        //响应respMessage_jsonObj到前端
        response.getWriter().println(respMessage_jsonObj);
    }


    /**
     * PUT, http://localhost:8080/teacher.ctl, 修改教师
     * <p>
     * 修改一个教师对象：将来自前端请求的JSON对象，更新数据库表中相同id的记录
     *
     * @param request
     * @param response
     * @throws ServletException
     * @throws IOException
     */
    @Override
    protected void doPut(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        //设置请求字符编码为UTF-8
        request.setCharacterEncoding("UTF-8");
        String teacherToUpdate_jsonStr = JSONUtil.getJSON(request);
        //将JSON字串解析为要修改的Teacher对象（有id的完整对象）
        Teacher teacherToUpdate = JSON.parseObject(teacherToUpdate_jsonStr, Teacher.class);
        //设置响应字符编码为UTF-8
        response.setContentType("application/json;charset=UTF-8");
        //创建JSON对象respMessage_jsonObj，以便往前端响应信息
        JSONObject respMessage_jsonObj = new JSONObject();        
        try {
            //到数据库表修改Teacher对象对应的记录
            TeacherService.getInstance().update(teacherToUpdate);
            respMessage_jsonObj.put("message", "修改成功");
        } catch (SQLException e) {
            respMessage_jsonObj.put("message", "数据库操作异常");
            //打印异常栈，方便调试（要用log4j代替）
            log.debug(e.getMessage());
        } catch (Exception e) {
            respMessage_jsonObj.put("message", "网络异常");
            //打印异常栈，方便调试（要用log4j代替）
            log.debug(e.getMessage());
        }
        //响应respMessage_jsonObj到前端
        response.getWriter().println(respMessage_jsonObj);
    }
}
